Addition curable resin composition and semiconductor package

ABSTRACT

An addition curable resin composition comprising a silphenylene oligomer skeleton-bearing organosilicon compound having at least two alkenyl groups per molecule cures into a product having both a satisfactory hardness and crack resistance.

CROSS-REFERENCE TO RELATED APPLICATION

This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2015-249509 filed in Japan on Dec. 22,2015, the entire contents of which are hereby incorporated by reference.

TECHNICAL FIELD

This invention relates to an addition curable resin composition,especially comprising an organosilicon compound bearing a silphenyleneoligomer skeleton within the molecule, and a semiconductor packageencapsulated with the cured composition.

BACKGROUND ART

From the past, addition curable silicone resin compositions are used asencapsulant for semiconductor chips such as LED because of fast cure andheat resistance and light resistance of cured products. For example,Patent Document 1 describes an addition curable silicone resincomposition which exhibits a high bond strength to LED packages ofthermoplastic resins, typically PPA. Patent Document 2 describes theencapsulation of an optoelectronic chip with an addition curablesilicone resin composition by compression molding.

Although addition curable silicone resin compositions are widely used assemiconductor encapsulant, their properties are still unsatisfactory.Particularly in the semiconductor encapsulant field where theencapsulating resin is stressed due to a temperature difference betweenthe ambient environment and during current conduction, materials havingcrack resistance are required. Because of poor crack resistance,silicone resins are susceptible to cracking. To solve the problem, gelor rubber-like soft silicone resins are used. When semiconductor chipsare encapsulated by compression molding using a compression mold ortransfer mold, the gel or rubber-like silicone resins are inadequatebecause they are so tacky, giving rise to a stick-in-mold problem. Thereis a need for silicone resins which have a sufficient hardness for moldrelease and are yet resistant to stresses.

For imparting toughness to a cured silicone resin while maintaininghardness, an attempt to incorporate a silphenylene skeleton into asilicone resin is made in Patent Documents 3 and 4. As compared with thegeneral method of establishing a high hardness by increasing thecrosslinking density of silicone resin, this method establishes a highhardness by incorporating a silphenylene skeleton into a silicone resinto restrain motion of the polymer chain. Thus the resin has rigidity andhardness. While the method of increasing the crosslinking densitygenerally makes the resin brittle, the method of incorporating asilphenylene skeleton is advantageous in that the resin exerts atoughness without embrittlement because the silphenylene skeleton islinear. However, the method of incorporating a silphenylene monomer intoa silicone resin skeleton as described in Patent Documents 3 and 4,achieves weak binding of the molecular chain and thus fails to form aresin having a high hardness and yet satisfactory stress resistance.

CITATION LIST

-   -   Patent Document 1: JP 5136963    -   Patent Document 2: JP-A 2006-093354    -   Patent Document 3: JP-A 2001-064393 (U.S. Pat. No. 6,368,535, EP        1074574)    -   Patent Document 4: JP-A 2005-133073

DISCLOSURE OF INVENTION

An object of the invention is to provide an addition curable resincomposition which cures into a product having a satisfactory hardnessand crack resistance, and a semiconductor package encapsulated with thecured composition (or comprising a cured product of the resincomposition).

The inventors have found that the above and other objects are attainedby using a silphenylene oligomer skeleton-bearing organosilicon compoundhaving at least two alkenyl groups per molecule, represented by thegeneral formula (1):(R¹ ₃SiO_(0.5))_(a)(R¹ ₂SiO)_(b)(R¹SiO_(1.5))_(c)(SiO₂)_(d)Z_(e)  (1)wherein R¹, Z, a, b, c, d, and e are as defined below. That is, anaddition curable resin composition comprising the silphenylene oligomerskeleton-bearing organosilicon compound of formula (1) cures into aproduct having a satisfactory hardness and crack resistance.

In one aspect, the invention provides an addition curable resincomposition comprising (A) a silphenylene oligomer skeleton-bearingorganosilicon compound having at least two alkenyl groups per molecule,represented by the general formula (1):(R¹ ₃SiO_(0.5))_(a)(R¹ ₂SiO)_(b)(R¹SiO_(1.5))_(c)(SiO₂)_(d)Z_(e)  (1)wherein R¹ is independently a C₁-C₁₂ monovalent hydrocarbon group freeof aliphatic unsaturation or C₂-C₆ alkenyl group, at least two of R¹groups per molecule being alkenyl, Z is independently a group having theformula (2):

wherein R² is independently a C₁-C₁₂ monovalent hydrocarbon group, and nis an integer of 1 to 3, a is an integer of 0 to 100, b is an integer of0 to 5,000, c is an integer of 0 to 500, d is an integer of 0 to 500, eis an integer of 1 to 500, and 2≤a+b+c≤5,000.

In a preferred embodiment, component (A) comprises (A-i) a silphenyleneoligomer skeleton-bearing branched organosilicon compound having atleast two alkenyl groups per molecule, represented by formula (1)wherein b is an integer of 0 to 1,000, and 1≤c+d≤1,000.

In another preferred embodiment, component (A) comprises (A-ii) asilphenylene oligomer skeleton-bearing linear organosilicon compoundhaving at least two alkenyl groups per molecule, represented by thegeneral formula (3):(R¹ ₃SiO_(0.5))₂(R¹ ₂SiO)_(b′)Z_(e′)  (3)wherein R¹ and Z are as defined above, at least two of R¹ groups permolecule being, alkenyl, b′ is an integer of 0 to 5,000, e′ is aninteger of 1 to 500, and 1≤b′+e′≤5,001.

The composition may further comprise (B) an organopolysiloxane having atleast two alkenyl groups per molecule, represented by the generalformula (4):(R¹ ₃SiO_(0.5))_(f)(R¹ ₂SiO)_(g)(R¹SiO_(1.5))_(h)(SiO)₂)_(k)  (4)wherein R¹ is as defined above, at least two of R¹ groups per moleculebeing alkenyl, f is an integer of 0 to 100, g is an integer of 0 to5,000, h is an integer of 0 to 500, k is an integer of 0 to 500, and2≤f+g+h≤5,000, in an amount of 5 to 500 parts by weight per 100 parts byweight of component (A) in total.

In a preferred embodiment, component (B) comprises (B-i) a branchedorganopolysiloxane having at least two alkenyl groups per molecule,represented by formula (4) wherein 1≤h+k≤1,000, in an amount of 50 to500 parts by weight per 100 parts by weight of component (A) in total.

In another preferred embodiment, component (B) comprises (B-ii) a linearorganopolysiloxane having at least two alkenyl groups per molecule,represented by the general formula (5):(R¹ ₃SiO_(0.5))₂(R¹ ₂SiO)_(g′)  (5)wherein R¹ is as defined above, at least two of R¹ groups per moleculebeing alkenyl, g′ is an integer of 0 to 5,000, in an amount of 5 to 200parts by weight per 100 parts by weight of component (A) in total.

The composition may further comprise (C) an organopolysiloxane having atleast two hydrosilyl groups per molecule, represented by the generalformula (6):(R³ ₃SiO_(0.5))_(p)(R³ ₂SiO)_(q)(R³SiO_(1.5))_(r)(SiO₂)_(s)  (6)wherein R³ is independently hydrogen or a C₁-C₁₂ monovalent hydrocarbongroup, at least two of R³ groups per molecule being hydrogen, p is aninteger of 0 to 100, q is an integer of 0 to 500, r is an integer of 0to 300, s is an integer of 0 to 300, and 2≤p+q+r≤500, and/or (D) ahydrosilyl-containing silphenylene compound represented by the generalformula (7):

wherein R³ is as defined above and m is an integer of 0 to 3, in suchamounts that a ratio of the total number of hydrosilyl groups incomponents (C) and (D) to the total number of alkenyl groups incomponents (A) and (B) ranges from 0.6/1 to 3/1.

The composition may further comprise (E) a hydrosilylation catalyst.

Also contemplated herein is a semiconductor package encapsulated with acured product of the addition curable resin composition defined above.

Advantageous Effects of Invention

The addition curable resin composition uses a silphenylene oligomerskeleton-bearing organosilicon compound having repeating silphenyleneskeleton units as a base polymer. The composition has toughness becausethe linear molecular chain becomes rigid and is extended, as comparedwith the use of a silphenylene monomer skeleton bearing organosiliconcompound. A cured product has both a satisfactory hardness and crackresistance.

DESCRIPTION OF PREFERRED EMBODIMENTS

The notation (Cn-Cm) means a group containing from n to m carbon atomsper group.

One embodiment of the invention is an addition curable resin compositioncomprising (A) a silphenylene oligomer skeleton-bearing organosiliconcompound having at least two alkenyl groups per molecule, represented bythe general formula (1).

(A) Silphenylene Oligomer Skeleton-Bearing Organosilicon Compound

Component (A) is a silphenylene oligomer skeleton-bearing organosiliconcompound having at least two alkenyl groups per molecule, represented bythe general formula (1).(R¹ ₃SiO_(0.5))_(a)(R¹ ₂SiO)_(b)(R¹SiO_(1.5))_(c)(SiO₂)_(d)Z_(e)  (1)Herein R¹ is independently a C₁-C₁₂ monovalent hydrocarbon group free ofaliphatic unsaturation, or C₂-C₆ alkenyl group, at least two of R¹groups per molecule being alkenyl. Z is independently a group having theformula (2):

wherein R² is independently a C₁-C₁₂ monovalent hydrocarbon group, and nis an integer of 1 to 3. The subscript a is an integer of 0 to 100, b isan integer of 0 to 5,000, c is an integer of 0 to 500, d is an integerof 0 to 500, e is an integer of 1 to 500, and 2≤a+b+c≤5,000.

In formula (1), R¹ is a C₁-C₁₂ monovalent hydrocarbon group free ofaliphatic unsaturation, or a C₂-C₆ alkenyl group, examples of whichinclude C₁-C₁₂ monovalent saturated aliphatic hydrocarbon groups, forexample, alkyl groups such as methyl, ethyl, propyl, butyl and hexyl,and cycloalkyl groups such as cyclohexyl, C₆-C₁₂ monovalent aromatichydrocarbon groups, for example, aryl groups such as phenyl, tolyl,xylyl and naphthyl and aralkyl groups such as benzyl, phenylethyl andphenylpropyl, and C₂-C₆ alkenyl groups such as vinyl, allyl andpropenyl. At least two of R¹ groups are alkenyl, preferably vinyl.Methyl and phenyl are preferred as R¹ other than alkenyl.

The organosilicon compound should have at least two alkenyl groups permolecule. An alkenyl content is preferably 0.0001 to 1.1 mol/100 g, morepreferably 0.0005 to 0.8 mol/100 g, and even more preferably 0.001 to0.5 mol/100 g of the organosilicon compound. The alkenyl groups may belocated in any of R¹ ₃SiO_(0.5) units, R¹ ₂SiO units and R¹SiO_(1.5)units or in plural units, preferably in R¹ ₃SiO_(0.5) units.

R² is a C₁-C₁₂ monovalent hydrocarbon group, examples of which includeC₁-C₁₂ monovalent saturated aliphatic hydrocarbon groups, for example,alkyl groups such as methyl, ethyl, propyl, butyl and hexyl, andcycloalkyl groups such as cyclohexyl, C₆-C₁₂ monovalent aromatichydrocarbon groups, for example, aryl groups such as phenyl, tolyl,xylyl and naphthyl and aralkyl groups such as benzyl, phenylethyl andphenylpropyl. The group R² should preferably be free of aliphaticunsaturation. Methyl and phenyl are preferred as R². The subscript n isan integer of 1 to 3, preferably 1.

In formula (1), a is an integer of 0 to 100, preferably 0 to 75, andmore preferably 0 to 50; b is an integer of 0 to 5,000, preferably 0 to1,000, more preferably 0 to 500, and even more preferably 0 to 250; c isan integer of 0 to 500, preferably 0 to 250, and more preferably 0 to125, d is an integer of 0 to 500, preferably 0 to 250, and morepreferably 0 to 125; e is an integer of 1 to 500, preferably 1 to 250,and more preferably 1 to 100; and 2≤a+b+c≤5,000, preferably2≤a+b+c≤1,000, more preferably 5≤a+b+c≤750, and even more preferably10≤a+b+c≤500.

The organosilicon compound may be prepared by any well-known methods.For example, it may be obtained from (co)hydrolytic condensation of asilphenylene oligomer having a hydrolyzable or hydroxyl group with ahydrolyzable silane or siloxane by a standard method. The silphenyleneoligomer having a hydrolyzable or hydroxyl group is represented by thegeneral formula (8):

wherein R² and n are as defined above, and X is a hydrolyzable orhydroxyl group.

In formula (8), examples of the hydrolyzable group X include C₁-C₁₀alkoxy groups such as methoxy, ethoxy, propoxy and butoxy, C₂-C₁₀alkoxyalkoxy groups such as methoxymethoxy and methoxyethoxy, C₁-C₁₀acyloxy groups such as acetoxy, C₂-C₁₀ alkenyloxy groups such asisopropenoxy, and halogen atoms such as chlorine, bromine and iodine.Preferably X is hydroxyl, chlorine, methoxy or ethoxy.

Examples of the silphenylene oligomer having formula (8) are givenbelow.

Component (A) may be used alone or in admixture of two or more. Of thesilphenylene oligomer skeleton-bearing organosilicon compounds ascomponent (A), (A-i) a branched organosilicon compound and/or (A-ii) alinear organosilicon compound is preferable.

(A-i) Silphenylene Oligomer Skeleton-Bearing Branched OrganosiliconCompound Having at Least Two Alkenyl Groups

Component (A-i) is a silphenylene oligomer skeleton-bearing branchedorganosilicon compound having at least two alkenyl groups per molecule,represented by formula (1) wherein b is an integer of 0 to 1,000, and1≤c+d≤1,000. Herein, R¹, Z, a, c, d, e and a+b+c are the same as definedabove, and at least two of R¹ groups per molecule are alkenyl. Thesubscript b is an integer of 0 to 1,000, preferably 0 to 500, and morepreferably 0 to 250, and 1≤c+d≤1,000, preferably 5≤c+d≤750, and morepreferably 10≤c+d≤500.

The organosilicon compound (A-i) should have at least two alkenyl groupsper molecule. An alkenyl content is preferably 0.01 to 0.5 mol/100 g,more preferably 0.05 to 0.3 mol/100 g of the organosilicon compound. Thealkenyl groups may be located in any of R¹ ₃SiO_(0.5) units, R¹ ₂SiOunits and R¹SiO_(1.5) units or in plural units, preferably in R¹₃SiO_(0.5) units.

(A-ii) Silphenylene Oligomer Skeleton-Bearing Linear OrganosiliconCompound Having at Least Two Alkenyl Groups

Component (A-ii) is a silphenylene oligomer skeleton-bearing linearorganosilicon compound having at least two alkenyl groups per molecule,represented by the general formula (3):(R¹ ₃SiO_(0.5))₂(R¹ ₂SiO)_(b′)Z_(e′)  (3)wherein R¹ and Z are as defined above, at least two of R¹ groups permolecule being alkenyl, b′ is an integer of 0 to 5,000, e′ is an integerof 1 to 500, and 1≤b′+e′≤5,001.

In formula (3), R¹ and Z are the same as defined above, and at least twoof R¹ groups per molecule are alkenyl. The subscript b′ is an integer of0 to 5,000, preferably 0 to 2,500, and more preferably 0 to 1,000; e′ isan integer of 1 to 500, preferably 1 to 350, and more preferably 1 to200; and 1≤b′+e′≤5,001, preferably 1≤b′+e′≤2,500 and more preferably1≤b′+e′≤1,000.

The organosilicon compound (A-ii) should have at least two alkenylgroups per molecule. An alkenyl content is preferably 0.0001 to 1.1mol/100 g, more preferably 0.0005 to 0.8 mol/100 g, and even morepreferably 0.001 to 0.5 mol/100 g of the organosilicon compound. Thealkenyl groups may be located in any of R¹ ₃SiO_(0.5) units and R¹ ₂SiOunits or in plural units, preferably in R¹ ₃SiO_(0.5) units.

Components (A-i) and (A-ii) may be used at the same time. When a mixtureof components (A-i) and (A-ii) is used, 100 parts by weight of component(A-i) is preferably combined with 5 to 500 parts by weight, morepreferably 10 to 300 parts by weight of component (A-ii).

While component (A) is essential to the inventive composition, component(B) may be optionally used in combination. Particularly when component(A) is (A-i) a branched organosilicon compound, a combination thereofwith (B-ii) a linear organopolysiloxane is preferred. When component (A)is (A-ii) a linear organosilicon compound, a combination thereof with(B-i) a branched organopolysiloxane is preferred. Notably component (B)may be used alone or in admixture.

(B) Organopolysiloxane Having at Least Two Alkenyl Groups

Component (B) is an organopolysiloxane having at least two alkenylgroups per molecule, represented by the general formula (4).(R¹ ₃SiO_(0.5))_(f)(R¹ ₂SiO)_(g)(R¹SiO_(1.5))_(h)(SiO₂)_(k)  (4)Herein R¹ is as defined above, at least two of R¹ groups per moleculebeing alkenyl, f is an integer of 0 to 100, g is an integer of 0 to5,000, h is an integer of 0 to 500, k is an integer of 0 to 500, and2≤f+g+h≤5,000.

In formula (4), R¹ is the same as defined above, and at least two of R¹groups per molecule are alkenyl. The subscript f is an integer of 0 to100, preferably 0 to 75, and more preferably 0 to 50; g is an integer of0 to 5,000, preferably 0 to 2,500, and more preferably 0 to 1,000; h isan integer of 0 to 500, preferably 0 to 250, and more preferably 0 to125; k is an integer of 0 to 500, preferably 0 to 250, and morepreferably 0 to 125; and 2≤f+g+h≤5,000, preferably 5≤f+g+h≤2,500, andmore preferably 10≤f+g+h≤1,000.

The organopolysiloxane (B) should have at least two alkenyl groups permolecule. An alkenyl content is preferably 0.0001 to 1.1 mol/100 g, morepreferably 0.0005 to 0.5 mol/100 g, and even more preferably 0.005 to0.3 mol/100 g of the organopolysiloxane. The alkenyl groups may belocated in any of R¹ ₃SiO_(0.5) units, R¹ ₂SiO units and R¹SiO_(1.5)units or in plural units, preferably in R¹ ₃SiO_(0.5) units.

An amount of component (B) used is preferably 5 to 500 parts by weight,more preferably 10 to 300 parts by weight per 100 parts by weight ofcomponent (A) in total. Within the range, component (B) does notadversely affect the crack resistance improving effect of component (A).

(B-i) Branched Organopolysiloxane Having at Least Two Alkenyl Groups

Component (B-i) is a branched organopolysiloxane having at least twoalkenyl groups per molecule, represented by formula (4) wherein1≤h+k≤1,000. Herein, R¹, f, g, h, k and f+g+h are the same as definedabove, and at least two of R¹ groups per molecule are alkenyl. Thesubscripts h and k meet 1≤h+k≤1,000, preferably 5≤h+k≤750, and morepreferably 10≤h+k≤500.

The organopolysiloxane (B-i) should have at least two alkenyl groups permolecule. An alkenyl content is preferably 0.01 to 0.5 mol/100 g, morepreferably 0.05 to 0.3 mol/100 g of the organopolysiloxane. The alkenylgroups may be located in any of R¹ ₃SiO_(0.5) units, R¹ ₂SiO units andR¹SiO_(1.5) units or in plural units, preferably in R¹ ₃SiO_(0.5) units.

An amount of component (B-i) is preferably 50 to 500 parts by weight,more preferably 100 to 300 parts by weight per 100 parts by weight ofcomponent (A) in total.

(B-ii) Linear Organopolysiloxane Having at Least Two Alkenyl Groups

Component (B-ii) is a linear organopolysiloxane having at least twoalkenyl groups per molecule, represented by the general formula (5):(R¹ ₃SiO_(0.5))₂(R¹ ₂SiO)_(g′)  (5)wherein R¹ is as defined above, at least two of R¹ groups per moleculebeing alkenyl, g′ is an integer of 0 to 5,000, preferably 1 to 2,500,and more preferably 2 to 1,000.

The organopolysiloxane (B-ii) should have at least two alkenyl groupsper molecule. An alkenyl content is preferably 0.0001 to 1.1 mol/100 g,more preferably 0.0005 to 0.8 mol/100 g, and even more preferably 0.001to 0.5 mol/100 g of the organopolysiloxane. The alkenyl groups may belocated in any of R¹ ₃SiO_(0.5) units and R¹ ₂SiO units or in pluralunits, preferably in R¹ ₃SiO_(0.5) units.

An amount of component (B-ii) used is preferably 5 to 200 parts byweight, more preferably 10 to 100 parts by weight per 100 parts byweight of component (A) in total.

In the addition curable resin composition, component (C) and/or (D) ispreferably used as a crosslinker.

(C) Organopolysiloxane Having at Least Two Hydrosilyl Groups

Component (C) is an organopolysiloxane having at least two hydrosilylgroups per molecule, represented by the general formula (6):(R³ ₃SiO_(0.5))_(p)(R³ ₂SiO)_(q)(R³SiO_(1.5))_(r)(SiO₂)_(s)  (6)wherein R³ is independently hydrogen or a C₁-C₁₂ monovalent hydrocarbongroup, at least two of R³ groups per molecule being hydrogen, p is aninteger of 0 to 100, q is an integer of 0 to 500, r is an integer of 0to 300, s is an integer of 0 to 300, and 2≤p+q+r≤500.

In formula (6), R³ is hydrogen or a C₁-C₁₂ monovalent hydrocarbon group,preferably free of aliphatic unsaturation. Examples of R³ includehydrogen, C₁-C₁₂ monovalent saturated aliphatic hydrocarbon groups, forexample, alkyl groups such as methyl, ethyl, propyl, butyl and hexyl,and cycloalkyl groups such as cyclohexyl, C₆-C₁₂ monovalent aromatichydrocarbon groups, for example, aryl groups such as phenyl, tolyl,xylyl and naphthyl and aralkyl groups such as benzyl, phenylethyl andphenylpropyl. At least two of R³ groups are hydrogen. Methyl and phenylare preferred as R³ other than hydrogen.

In formula (6), p is an integer of 0 to 100, preferably 0 to 75, andmore preferably 0 to 50; q is an integer of 0 to 500, preferably 0 to300, and more preferably 0 to 150; r is an integer of 0 to 300,preferably 0 to 200, and more preferably 0 to 100; s is an integer of 0to 300, preferably 0 to 200, and more preferably 0 to 100; and2≤p+q+r≤500, preferably 2≤p+q+r≤300, and more preferably 3≤p+q+r≤200.

The organopolysiloxane should have at least two hydrogen atoms permolecule. A hydrogen content is preferably 0.1 to 2 mol/100 g, morepreferably 0.2 to 1.8 mol/100 g of the organopolysiloxane. The hydrogenatoms may be located in any of R³ ₃SiO_(0.5) units, R³ ₂SiO units andR³SiO_(1.5) units or in plural units, preferably in R³ ₃SiO_(0.5) units.

Component (C) may be used alone or in admixture.

An appropriate amount of component (C) used is such that a ratio of thenumber of hydrosilyl groups to the total number of alkenyl groups incomponents (A) and (B) may range from 0.6/1 to 3/1, more preferably from0.7/1 to 2/1, and even more preferably from 0.8/1 to 1.5/1. A ratiobelow the lower limit indicates shortage of SiH groups and under-cure.Above the upper limit, residual SiH groups tend to induce side reactionssuch as dehydrogenation.

(D) Hydrosilyl-Containing Silphenylene Compound

Component (D) is a hydrosilyl-containing silphenylene compoundrepresented by the general formula (7):

wherein R³ is as defined above and m is an integer of 0 to 3.

In formula (7), R³ is as defined above and m is an integer of 0 to 3,preferably 0 to 2, and most preferably 1.

Component (D) may be used alone or in admixture.

An appropriate Amount of component (D) used is such that a ratio of thenumber of hydrosilyl groups to the total number of alkenyl groups incomponents (A) and (B) may range from 0.6/1 to 3/1, more preferably from0.7/1 to 2/1, and even more preferably from 0.8/1 to 1.5/1. A ratiobelow the lower limit indicates shortage of SiH groups and under-cure.Above the upper limit, residual SiH groups tend to induce side reactionssuch as dehydrogenation.

When component (D) is used in combination with component (C), amounts ofcomponents (C) and (D) are adjusted such that a ratio of the totalnumber of hydrosilyl groups in components (C) and (D) to the totalnumber of alkenyl groups in components (A) and (B) may range from 0.6/1to 3/1, more preferably from 0.7/1 to 2/1, and even more preferably from0.8/1 to 1.5/1. Components (C) and (I)) are preferably combined in sucha ratio that component (C) is 5 to 95%, more preferably 10 to 90%, andeven more preferably 20 to 80% by weight based on the total weight ofcomponents (C) and (D).

(E) Hydrosilylation Catalyst

In the resin composition, (E) a hydrosilylation catalyst may be used forthe purpose of promoting hydrosilylation cure. The catalyst is notparticularly limited and may be selected from well-known ones. Preferredare platinum group metal elements and platinum group metal compounds.Suitable catalysts include platinum base catalysts such as platinum(inclusive of platinum black), platinum chloride, chloroplatinic acid,platinum-olefin complexes such as platinum-divinylsiloxane complex, andplatinum-carbonyl complexes, palladium base catalysts and rhodium basecatalysts. These catalysts may be used alone or in admixture. Interalia, chloroplatinic acid and platinum-olefin complexes such asplatinum-divinylsiloxane complex are preferred.

The amount of component (E) used is not particularly limited and may bea catalytic amount. The catalytic amount is a sufficient amount foraddition reaction to take place and may be determined as appropriate inaccordance with the desired cure rate. In an example where the platinumgroup metal catalyst is used, it is preferred from the standpoint ofreaction rate that the catalyst be used in such an amount as to provide0.1 to 50 ppm, more preferably 1 to 10 ppm of platinum group metal basedon the total weight of components (A) to (D).

In addition to the above components (A) to (E), the addition curableresin composition may include optional additives such as phosphor,inorganic filler, adhesive aid, and cure inhibitor. These additives aredescribed below.

Phosphor

The phosphor used herein is not particularly limited and any well-knownphosphors may be used. One preferred example is the phosphor capable ofabsorbing light from a semiconductor chip, typically a semiconductor LEDincluding a light-emissive layer of nitride semiconductor and convertingit to light of different wavelength. Suitable such phosphors includenitride base phosphors and oxynitride base phosphors which are activatedmainly with a lanthanoid element such as Eu or Ce; alkaline earth metalhalide apatite phosphors which are activated mainly with a lanthanoidelement such as Eu or a transition metal element such as Mn, alkalineearth metal borate halide phosphors, alkaline earth metal aluminatephosphors, alkaline earth metal silicate phosphors, alkaline earth metalsulfide phosphors, alkaline earth metal thiogallate phosphors, alkalineearth metal silicon nitride phosphors, and germanate phosphors; rareearth aluminate phosphors which are activated mainly with a lanthanoidelement such as Ce; rare earth silicate phosphors; organic and organiccomplex phosphors which are activated mainly with a lanthanoid elementsuch as Eu; and Ca—Al—Si—O—N oxynitride glass phosphors, which may beused alone or in admixture.

Exemplary of the nitride phosphors which are activated mainly with alanthanoid element such as Eu or Ce are M₂Si₅N₈:Eu wherein M is at leastone element selected from Sr, Ca, Ba, Mg, and Zn. Also included areMSi₇N₁₀:Eu, M_(1.8)Si₅O_(0.2)N₈:Eu, and M_(0.9)Si₇O_(0.1)N₁₀:Eu whereinM is at least one element selected from Sr, Ca, Ba, Mg, and Zn.

Exemplary of the oxynitride phosphors which are activated mainly with alanthanoid element such as Eu or Ce are MSi₂O₂N₂:Eu wherein M is atleast one element selected from Sr, Ca, Ba, Mg, and Zn.

Exemplary of the alkaline earth metal halide apatite phosphors which areactivated mainly with a lanthanoid element such as Eu or a transitionmetal element such as Mn are M₅(PO₄)₃X′:R′ wherein M is at least oneelement selected from Sr, Ca, Ba, Mg, and Zn, X′ is at least one elementselected from F, Cl, Br and T, and R′ Is En, Mn, or Eu and Mn.

Exemplary of the alkaline earth metal borate halide phosphors areM₂B₅O₉X′:R′ wherein M is at least one element selected from Sr, Ca, Ba,Mg, and Zn, X′ is at least one element selected from F, Cl, Br and I,and R′ is Eu, Mn, or Eu and Mn.

Exemplary of the alkaline earth metal aluminate phosphors areSrAl₂O₄:R′, Sr₄Al₁₄O₂₅:R′, CaAl₂O₄:R′, BaMg₂Al₁₆O₂₇:R′, BaMg₂Al₁₆O₁₂:R′and BaMgAl₁₀O₁₇:R′ wherein R′ is Eu, Mn, or Eu and Mn.

Exemplary of the alkaline earth metal sulfide phosphors are La₂O₂S:Eu,Y₂O₂S:Eu and Gd₂O₂S:Eu.

Exemplary of the rare earth aluminate phosphors which are activatedmainly with a lanthanoid element such as Ce are YAG base phosphors ofthe compositional formulae: Y₃Al₅O₁₂:Ce, (Y_(0.8)Gd_(0.2))₃Al₅O₁₂:Ce,Y₃(Al_(0.8)Ga_(0.2))₅O₁₂:Ce, and (Y,Gd)₃(Al,Ga)₅O₁₂:Ce. Also includedare variants of the foregoing wherein Y is partly or entirely replacedby Tb or Lu, such as Tb₃Al₅O₁₂:Ce and Lu₃Al₅O₁₂:Ce.

Other suitable phosphors include ZnS:Eu, Zn₂GeO₄:Mn, and MGa₂S₄:Euwherein M is at least one element selected from Sr, Ca, Ba, Mg, and Zn.

In the above phosphors, at least one element selected from Tb, Cu, Ag,Au, Cr, Nd, Dy, Co, Ni and Ti may be incorporated instead of Eu or inaddition to Eu, if desired.

The Ca—Al—Si—O—N oxynitride glass phosphors are phosphors based on anoxynitride glass matrix consisting of 20 to 50 mol % of CaCO₃(calculated as CaO), 0 to 30 mol % of Al₂O₃, 25 to 60 mol % of SiO, 5 to50 mol % of AlN, and 0.1 to 20 mol % of a rare earth oxide or transitionmetal oxide, the total of five ingredients being 100 mol %. In thephosphors based on an oxynitride glass matrix, the nitrogen content ispreferably up to 15 mol %, and besides the rare earth oxide ion, anotherrare earth ion serving as a sensitizer is preferably contained in thephosphor glass in a content of 0.1 to 10 mol % of rare earth oxide as aco-activator.

Phosphors other than the foregoing may also be used as long as they haveequivalent functions and effects.

The phosphor takes the form of particles having an average particle sizeof preferably at least 10 nm, more preferably 10 nm to 10 μm, and evenmore preferably 10 nm to 1 μm. Notably, the average particle size ismeasured by a particle size distribution measurement system CILAS usingthe laser light diffraction method.

When added, the amount of the phosphor is preferably 0.1 to 2,000 parts,more preferably 0.1 to 100 parts by weight per 100 parts by weight ofthe other components, typically components (A) to (E) combined. When thecured product of the addition curable resin composition takes the formof a phosphor-containing film for wavelength conversion, the phosphoramount is preferably 10 to 2,000 parts by weight.

Inorganic Filler

Suitable inorganic fillers include silica, fumed silica, fumed titaniumdioxide, alumina, calcium carbonate, calcium silicate, titanium dioxide,ferric oxide, and zinc oxide, which may be used alone or in admixture.When added, the amount of the filler is preferably up to 20 parts, morepreferably 0.1 to 10 parts by weight per 100 parts by weight ofcomponents (A) to (E) combined, but not limited thereto.

Adhesive Aid

An adhesive aid may be added to the resin composition for impartingadhesion thereto, if desired. Suitable adhesive aids are organosiloxaneoligomers of preferably 4 to 50 silicon atoms, more preferably 4 to 20silicon atoms, having at least one substituent selected fromsilicon-bonded hydrogen and alkenyl and at least one of hydroxysilylgroup, alkoxy group, epoxy group and nitrogen-containing substituent.These oligomers differ from components (A) to (D) in that they contain ahydroxysilyl group, alkoxy group, epoxy group or nitrogen-containingsubstituent.

Also useful as the adhesive aid are organooxysilyl-modified isocyanuratecompounds having the formula (9) below and hydrolytic condensatesthereof (i.e., organosiloxane-modified isocyanurate compounds).

In formula (9), R⁴ is each independently an organic group having theformula (10) below, or a monovalent unsaturated aliphatic hydrocarbongroup which may contain an oxygen atom, with the proviso that at leastone R⁴ is an organic group of formula (10).

Herein R⁵ is hydrogen or a C₁-C₆ monovalent hydrocarbon group such asmethyl or ethyl, and t is an integer of 1 to 6, preferably 1 to 4.

In formula (9), the monovalent unsaturated aliphatic hydrocarbon grouprepresented by R⁴ may optionally contain oxygen, and is preferablyselected from hydrocarbon groups of 2 to 8 carbon atoms, more preferably2 to 6 carbon atoms, for example, linear or branched alkenyl groups suchas vinyl, allyl, 1-butenyl, 1-hexenyl and 2-methylpropenyl, and(meth)acrylic groups.

When added, the amount of the adhesive aid is preferably up to 10 parts,more preferably 0.1 to 8 parts, and even more preferably 0.2 to 5 partsby weight per 100 parts by weight of components (A) to (E) combined. Aslong as the amount is equal to or less than the upper limit, the curedproduct has a high hardness and a less surface tack.

The adhesive aid is preferably added in such amounts that the ratio ofthe total number of hydrosilyl groups in the entire composition(inclusive of the adhesive aid) to the total number of alkenyl groups inthe entire composition may range from 0.4/1 to 4/1, more preferably0.6/1 to 3/1, and even more preferably 0.8/1 to 2/1.

Further the adhesive aid is preferably added in an amount of 0.01 to10%, more preferably 0.1 to 5% by weight based on the total weight ofcomponents (A) to (E). This range of the adhesive aid is effective forimproving the adhesion of the composition without sacrificing itsbenefits.

Cure Inhibitor

A cure inhibitor may be added to the resin composition for controllingreactivity to enhance shelf stability, if desired. Suitable cureinhibitors include triallyl isocyanurate, alkyl maleates, acetylenealcohols, silane or siloxane-modified products thereof, hydroperoxide,tetramethylethylenediamine, benzotriazole, and mixtures thereof. Whenadded, the amount of the cure inhibitor is preferably 0.001 to 1 part,more preferably 0.005 to 0.5 part by weight per 100 parts by weight ofcomponents (A) to (E) combined.

Other Additives

Besides the above components, other additives may be added to the resincomposition. Suitable additives include a radical scavenger, flameretardant, surfactant, photostabilizer, thickener, plasticizer,antioxidant, heat stabilizer, conductive agent, antistatic agent,radiation shielding agent, nucleating agent, phosphorus peroxidedecomposing agent, lubricant, pigment, metal inactivating agent,physical property regulator, and organic solvent. These optionaladditives may be used alone or in admixture.

The simplest embodiment of the addition curable resin composition is acomposition consisting of components (A), (C) and (E). Particularly whenit is desired that a cured product have high transparency, thecomposition should preferably be free of an inorganic filler such assilica filler. Examples of the inorganic filler are as described above.

The method for preparing the addition curable resin composition is notparticularly limited. The composition may be prepared by any prior artwell-known methods, for example, by mixing components (A) to (E), andoptional components in a standard way. For example, the components arefed into a commercially available mixer (e.g., Thinky Conditioning Mixerby Thinky Corp.) where they are mixed for about 1 to 5 minutes untiluniform.

The method for curing the addition curable resin composition is notparticularly limited. The composition may be cured by any prior artwell-known methods, for example, by heating at 60 to 180° C. for about 1to 12 hours. Preferably the composition is cured stepwise. The stepwisecuring includes two steps, for example. The resin composition is heatedat a temperature of 60 to 100° C. for 0.5 to 2 hours for achieving fulldeaeration before it is heated at a temperature of 120 to 180° C. for 1to 10 hours for heat curing. Such stepwise curing ensures that even whenthe composition to be cured is thick walled, it is fully cured into acolorless transparent product without bubbles. The term “colorlesstransparent product” means that a cured part of 1 mm thick has a lighttransmittance of at least 80%, preferably at least 85%, and mostpreferably at least 90% at wavelength 450 nm.

Since the addition curable resin composition cures into a product havinga high light transmittance, it is suited for the encapsulation of LEDchips, especially blue and purple LED chips. An LED chip ormicroelectronic device may be encapsulated with the addition curableresin composition by any prior art well-known methods, for example,dispensing or compression molding.

Since the addition curable resin composition cures into a product havingcrack resistance, heat resistance, light resistance and transparency aswell as an appropriate hardness, it is also suited in a variety ofapplications including display materials, optical recording mediamaterials, optional equipment materials, optical part materials, opticalfiber materials, optoelectronic functional organic materials, andsemiconductor IC-related materials.

EXAMPLE

Examples of the invention are given below by way of illustration and notby way of limitation. In Examples, all parts are by weight (pbw) unlessotherwise indicated.

Proton nuclear magnetic resonance (¹H-NMR) spectra were measured on aspectrometer ULTRASHIELD® 400PLUS (Bruker).

The Vi value (mol/100 g) and SiH value (mol/1.00 g) shown below weredetermined by measuring a ¹H-NMR spectrum of the compound at 400 MHz,and computing integrated values of hydrogen atoms using dimethylsulfoxide as internal standard.

Components (A) to (F) used in Examples have the following structures. Mestands for methyl, Ph for phenyl, and Vi for vinyl, and Z, Z′ and Y havethe following formulae.

-   (A-1) Branched organosilicon compound of the formula below    (Shin-Etsu Chemical Co., Ltd., Vi value=0.177 mol/100 g)    (Vi(Me)₂SiO_(0.5))₃(PhSiO_(1.5))₇Z_(1.5)-   (A-2) Branched organosilicon compound of the formula below    (Shin-Etsu Chemical Co., Ltd., Vi value=0.214 mol/100 g)    (Vi(Me)₂SiO_(0.5))₁₅((Me)₃SiO_(0.5))₁₅(SiO₂)₄₅Z₅-   (A-3) Branched organosilicon compound of the formula below    (Shin-Etsu Chemical Co., Ltd., Vi value=0.151 mol/100 g)    (Vi(Me)₂SiO_(0.5))₆₀((Me)₃SiO_(0.5))₁₂₀(SiO)₁₈₀Z₄₀-   (A-4) Branched organosilicon compound of the formula below    (Shin-Etsu Chemical Co., Ltd., Vi value=0.111 mol/100 g)    ((Me)₃SiO_(0.5))₆₀(ViMeSiO)₃₀(MeSiO_(1.5))₁₉₀Z₂₀-   (A-5) Linear organosilicon compound of the formula below (Shin-Etsu    Chemical Co., Ltd., Vi value=0.379 mol/100 g)    (Vi(Me)₂SiO_(0.5))₂Z₁-   (A-6) Linear organosilicon compound of the formula below (Shin-Etsu    Chemical Co., Ltd., Vi value=0.302 mol/100 g)    (Vi(Me)₂SiO_(0.5))₂Z′₁-   (A-7) Linear organosilicon compound of the formula below (Shin-Etsu    Chemical Co., Ltd., Vi value=0.043 mol/100 g)    (Vi(Me)₂SiO_(0.5))₂(PhMeSiO)₂₈Z₂-   (A-8) Linear organosilicon compound of the formula below (Shin-Etsu    Chemical Co., Ltd., Vi value−0.005 mol/100 g)    (Vi(Me)₂SiO_(0.5))₂(Me₂SiO)₃₀₀Z₄₅-   (A-9) Linear organosilicon compound of the formula below (Shin-Etsu    Chemical Co., Ltd., Vi value=0.001 mal/100 g)    (Vi(Me)₂SiO_(0.5))₂(Me₂SiO)₁₉₈₀Z₄₉₅-   (B-1) Branched silicone of the formula below (Shin-Etsu Chemical    Co., Ltd., Vi value=0.208 mal/100 g)    (Vi(Me)₂SiO_(0.5))_(2.5)(PhSiO_(1.5))_(7.5)-   (B-2) Branched silicone of the formula below (Shin-Etsu Chemical    Co., Ltd., Vi value=0.282 mol/100 g)    (Vi(Me)₂SiO_(0.5))_(3.5)(Me₃SiO_(0.5))₁₅(SiO₂)₄₅-   (B-3) Linear silicone of the formula below (Shin-Etsu Chemical Co.,    Ltd., Vi value=0.047 mal/100 g)    (Vi(Me)₂SiO_(0.5))₂(PhMeSiO)₃₀-   (B-4) Linear silicone of the formula below (Shin-Etsu Chemical Co.,    Ltd., Vi value=0.009 mol/100 g)    (Vi(Me)₂SiO_(0.5))₂(Me₂SiO)₃₀₀-   (C-1) Linear silicone of the formula below (Shin-Etsu Chemical Co.,    Ltd., SiH value=0.602 mol/100 g)    (H(Me)₂SiO_(0.5))₂(Ph₂SiO)₁-   (C-2) Branched silicone of the formula below (Shin-Etsu Chemical    Co., Ltd., SiH value=0.602 mol/100 g)    (H(Me)₂SiO_(0.5))₄(PhSiO_(1.5))₂-   (C-3) Linear silicone of the formula below (Shin-Etsu Chemical Co.,    Ltd., SiH value=1.556 mol/100 g)    (Me₃SiO_(0.5))₂(MeHSiO)₃₈-   (D) Organosilicon compound of the formula below (Shin-Etsu Chemical    Co., Ltd., SiH value=0.610 mol/100 g)

-   (F-1) Branched organosilicon compound of the formula below    (Shin-Etsu Chemical Co., Ltd., Vi value=0.198 mol/100 g)    (Vi(Me)₂SiO_(0.5))₃(PhSiO_(1.5))₇Y_(1.5)-   (F-2) Linear organosilicon compound of the formula below (Shin-Etsu    Chemical Co., Ltd., Vi value=0.045 mol/100 g)    (Vi(Me)₂SiO_(0.5))₂(PhMeSiO)₂₈Y₂-   (E) Chloroplatinic acid-divinyltetramethyldisiloxane complex    (Shin-Etsu Chemical Co., Ltd., Pt content 2 wt %)

Examples 1 to 12 and Comparative Examples 1 to 3

Curable resin compositions were prepared by mixing the componentsexclusive of the catalyst (E) in the amounts shown in Tables 1 and 2,adding an amount of the catalyst (E) so as to give 2 ppm of platinumbased on the total weight of the composition, and further mixing them.These resin compositions were examined by the following tests. In Tables1 and 2, the value of H/Vi is a ratio of the total number of hydrosilylgroups to the total number of vinyl groups in the overall composition.

(1) Viscosity of Resin Composition

A viscosity at 23° C. of the curable resin composition was measuredaccording to JIS Z 8803:2011 by a Brookfield viscometer.

(2) Hardness of Cured Product

The resin composition was cast into an aluminum dish of 50 mm diameterand 10 mm thick, and cured stepwise at 60° C. for 1 hour, at 100° C. for1 hour, and at 150° C. for 4 hours into a cured product. The curedproduct was measured for Shore D or Durometer Type A hardness accordingto JIS K 6253-3:2012.

(3) Light Transmittance of Cured Product

A concave polytetrafluoroethylene spacer of 1 mm thick was sandwichedbetween two slide glass plates of 50 mm×20 mm×1 mm thick and fixedlysecured. The resin composition was cast into the space, and curedstepwise at 60° C. for 1 hour, at 100° C. for 1 hour, and at 150° C. for4 hours. The cured sample was measured for light transmittance atwavelength 450 nm on a spectrometer U-4100 (Hitachi High-TechnologiesCorp.).

(4) Heat Resistance

The sample in test (3) was allowed to stand at 150° C. for 1,000 hoursbefore it was measured for light transmittance at 450 nm on spectrometerU-4100.

(5) Tensile Strength and Elongation at Break of Cured Product

The resin composition was cast into a concave polytetrafluoroethylenemold of 150 mm×200 mm×2 mm thick and cured stepwise at 60° C. for 1hour, at 100° C. for 1 hour, and at 150° C. for 4 hours. The curedsample was measured for tensile strength and elongation at break on atensile tester EZ TEST (EZ L by Ghimadzu Corp.) according Lu JIS K6251:2010 under conditions including a separation rate of 500 mm/min, adistance between grips of 80 mm, and a distance between two gage marksof 40 mm.

(6) Thermal Cycling Test

The resin composition was dispensed on a package (Tiger 3528, Shin-EtsuChemical Co., Ltd.) and cured stepwise at 60° C. for 1 hour, at 100° C.for 1 hour, and at 150° C. for 4 hours, obtaining a test sample in theform of the package encapsulated with the cured product. On twenty testsamples, a thermal cycling test (TCT) between −50° C. and 140° C. wascarried out over 1,000 cycles. The number of test samples in which theencapsulant cracked was counted.

The test results are shown in Tables 3 and 4.

TABLE 1 Amount Example (pbw) 1 2 3 4 5 6 7 8 (A-1) 100 100 100 100 100100 (A-2) 100 (A-3) 100 (A-4) (A-5) (A-6) (A-7) 50 50 50 50 (A-8) 450(A-9) (B-1) (B-2) (B-3) 10 200 (B-4) 200 (C-1) 30 28 16.5 28.5 30 (C-2)2.5 2.5 15 (C-3) 17.5 20 (D) 35 1.5 16.5 (F-1) (F-2) (E) amount to givea Pt content of 2 ppm H/Vi 1.01 1.17 0.90 1.01 0.94 1.09 1.18 1.78

TABLE 2 Amount Example Comparative Example (pbw) 9 10 11 12 1 2 3 (A-1)(A-2) (A-3) (A-4) 100 (A-5) 100 (A-6) 100 (A-7) 100 (A-8) (A-9) 5 (B-1)500 500 50 100 (B-2) 100 (B-3) 50 (B-4) 200 200 (C-1) 10 36 33.6 (C-2) 43 2.8 (C-3) 24 22.5 (D) 225 215 (F-1) 100 (F-2) 50 (E) amount to give aPt content of 2 ppm H/Vi 2.90 0.97 0.98 0.62 1.03 1.17 1.01

TABLE 3 Example Test results 1 2 3 4 5 6 7 8 Viscosity (Pa · s) 23° C.5.6 5.2 5.9 5 13.1 3.5 4.6 6.3 Hardness Shore D 33 51 30 42 58 — — —Type A — — — — — 75 88 41 Light Initial 99.7 99.8 99.6 99.6 99.7 99.799.7 99.6 transmittance After 150° C./ 99.3 99.4 99.3 99.2 99.3 99.399.5 99.3 [1 mm thick, 1,000 hr 450 nm] (% T) Tensile strength 25° C.5.4 7.1 5 5.9 8.7 4 10.1 3.9 (MPa) Elongation at 25° C. 120 90 140 10050 160 80 150 break (%) TCT −50° C. 

 140° C. 0/20 0/20 0/20 0/20 0/20 0/20 0/20 0/20 (number of 1,000 cyclescracked samples)

TABLE 4 Comparative Example Example Test results 9 10 11 12 1 2 3Viscosity (Pa · s) 23° C. 4.5 1.8 2.8 4.8 3.6 6.2 4.2 Hardness Shore D —64 68 — 24 — 28 Type A 73 — — 78 — 78 — Light Initial 99.6 99.7 99.899.7 99.7 99.6 99.8 transmittance After 150° C./ 99.4 99.1 99.2 99.399.2 99.3 99.3 [1 mm thick, 1,000 hr 450 nm] (% T) Tensile strength 25°C. 8.2 7.2 8 4.4 3.2 8.1 3.9 (MPa) Elongation at 25° C. 120 70 60 160 6050 80 break (%) TCT −50° C. 

 140° C. 0/20 0/20 0/20 0/20 18/20 20/20 10/20 (number of 1,000 cyclescracked samples)

It is evident from Tables 3 and 4 that the curable resin compositionscontaining a silphenylene oligomer skeleton-bearing organosiliconcompound (Examples 1 to 12) cure into products which are hard, but haveacceptable elongation and satisfactory mechanical strength, in contrastto the curable resin compositions consisting of organopolysiloxanes(Comparative Examples 1 and 2). The curable resin composition containinga silphenylene monomer skeleton-bearing organosilicon compound(Comparative Example 3) cures into a product which shows improvements inhardness and elongation, but is less effective in TCT, i.e.,insufficient in crack resistance, as opposed to the curable resincompositions containing a silphenylene oligomer skeleton-bearingorganosilicon compound. It has been demonstrated that the resincomposition containing a silphenylene oligomer skeleton-bearingorganosilicon compound endows the cured product with rigidity andtoughness.

The addition curable resin composition containing a silphenyleneoligomer skeleton-bearing organosilicon compound according to theinvention cures into a product having satisfactory mechanical propertiesand heat resistance. By encapsulating a semiconductor chip with thecured resin composition, a fully reliable semiconductor package isobtained. Since the cured product has high light transmittance, theresin composition is best suited for the encapsulation of LED chips,especially blue and purple LED chips.

Japanese Patent Application No. 2015-249509 is incorporated herein byreference.

Although some preferred embodiments have been described, manymodifications and variations may be made thereto in light of the aboveteachings. It is therefore to be understood that the invention may bepracticed otherwise than as specifically described without departingfrom the scope of the appended claims.

The invention claimed is:
 1. An addition curable resin compositioncomprising a component (A) which is a silphenylene oligomerskeleton-bearing organosilicon compound having at least two alkenylgroups per molecule, represented by the general formula (1):(R¹ ₃SiO_(0.5))_(a)(R¹ ₂SiO)_(b)(R¹SiO_(1.5))_(c)(SiO₂)_(d)Z_(e)  (1)wherein R¹ is independently a C₁-C₁₂ monovalent hydrocarbon group freeof aliphatic unsaturation or C₂-C₆ alkenyl group, at least two of R¹groups per molecule being alkenyl, Z is independently a group having theformula (2):

wherein R² is independently a C₁-C₁₂ monovalent hydrocarbon group, and nis an integer of 1 to 3, and a is an integer of 0 to 100, b is aninteger of 0 to 5,000, c is an integer of 0 to 500, d is an integer of 0to 500, e is an integer of 1 to 500, and 2≤a+b+c≤5,000, wherein saidcomponent (A) comprises (A-i) a silphenylene oligomer skeleton-bearingbranched organosilicon compound having at least two alkenyl groups permolecule, represented by formula (1) wherein b is an integer of 0 to1,000, and 1≤c+d≤1,000.
 2. An addition curable resin compositioncomprising (A) a silphenylene oligomer skeleton-bearing organosiliconcompound having at least two alkenyl groups per molecule, represented bythe general formula (1):(R¹ ₃SiO_(0.5))_(a)(R¹ ₂SiO)_(b)(R¹SiO_(1.5))_(c)(SiO₂)_(d)Z_(e)  (1)wherein R¹ is independently a C₁-C₁₂ monovalent hydrocarbon group freeof aliphatic unsaturation or C₂-C₆ alkenyl group, at least two of R¹groups per molecule being alkenyl, Z is independently a group having theformula (2):

wherein R² is independently a C₁-C₁₂ monovalent hydrocarbon group, and nis an integer of 1 to 3, and a is an integer of 0 to 100, b is aninteger of 0 to 5,000, c is an integer of 0 to 500, d is an integer of 0to 500, e is an integer of 1 to 500, and 2≤a+b+c≤5,000, wherein saidcomponent (A) comprises (A-ii) a silphenylene oligomer skeleton-bearinglinear organosilicon compound having at least two alkenyl groups permolecule, represented by the general formula (3):(R¹ ₃SiO_(0.5))₂(R¹ ₂SiO)_(b′)Z_(e′)  (3) wherein R¹ and Z are asdefined above, at least two of R¹ groups per molecule being alkenyl, b′is an integer of 0 to 5,000, e′ is an integer of 1 to 500, and1≤b′+e′≤5,001.
 3. An addition curable resin composition comprising (A) asilphenylene oligomer skeleton-bearing organosilicon compound having atleast two alkenyl groups per molecule, represented by the generalformula (1):(R¹ ₃SiO_(0.5))_(a)(R¹ ₂SiO)_(b)(R¹SiO_(1.5))_(c)(SiO₂)_(d)Z_(e)  (1)wherein R¹ is independently a C₁-C₁₂ monovalent hydrocarbon group freeof aliphatic unsaturation or C₂-C₆ alkenyl group, at least two of R¹groups per molecule being alkenyl, Z is independently a group having theformula (2):

wherein R² is independently a C₁-C₁₂ monovalent hydrocarbon group, and nis an integer of 1 to 3, and a is an integer of 0 to 100, b is aninteger of 0 to 5,000, c is an integer of 0 to 500, d is an integer of 0to 500, e is an integer of 1 to 500, and 2≤a+b+c≤5,000, and (B) anorganopolysiloxane having at least two alkenyl groups per molecule,represented by the general formula (4):(R¹ ₃SiO_(0.5))_(f)(R¹ ₂SiO)_(g)(R¹SiO_(1.5))_(h)(SiO₂)_(k)  (4) whereinR¹ is as defined above, at least two of R¹ groups per molecule beingalkenyl, f is an integer of 0 to 100, g is an integer of 0 to 5,000, hisan integer of 0 to 500, k is an integer of 0 to 500, and 2≤f+g+h≤5,000,in an amount of 5 to 500 parts by weight per 100 parts by weight of thetotal weight of component (A) in the composition.
 4. The composition ofclaim 3 wherein component (B) comprises (B-i) a branchedorganopolysiloxane having at least two alkenyl groups per molecule,represented by formula (4) wherein 1≤h+k≤1,000, in an amount of 50 to500 parts by weight per 100 parts by weight of the total weight ofcomponent (A) in the composition.
 5. The composition of claim 3 whereincomponent (B) comprises (B-ii) a linear organopolysiloxane having atleast two alkenyl groups per molecule, represented by the generalformula (5):(R¹ ₃SiO_(0.5))₂(R¹ ₂SiO)_(g′)  (5) wherein R¹ is as defined above, atleast two of R¹ groups per molecule being alkenyl, g′ is an integer of 0to 5,000, in an amount of 5 to 200 parts by weight per 100 parts byweight of the total weight of component (A) in the composition.
 6. Anaddition curable resin composition comprising (A) a silphenyleneoligomer skeleton-bearing organosilicon compound having at least twoalkenyl groups per molecule, represented by the general formula (1):(R¹ ₃SiO_(0.5))_(a)(R¹ ₂SiO)_(b)(R¹SiO_(1.5))_(c)(SiO₂)_(d)Z_(e)  (1)wherein R¹ is independently a C₁-C₁₂ monovalent hydrocarbon group freeof aliphatic unsaturation or C₂-C₆ alkenyl group, at least two of R¹groups per molecule being alkenyl, Z is independently a group having theformula (2):

wherein R² is independently a C₁-C₁₂ monovalent hydrocarbon group, and nis an integer of 1 to 3, and a is an integer of 0 to 100, b is aninteger of 0 to 5,000, c is an integer of 0 to 500, d is an integer of 0to 500, e is an integer of 1 to 500, and 2≤a+b+c≤5,000, optionally, (B)an organopolysiloxane having at least two alkenyl groups per molecule,represented by the general formula (4):(R¹ ₃SiO_(0.5))_(f)(R¹ ₂SiO)_(g)(R¹SiO_(1.5))_(h)(SiO₂)_(k)  (4) whereinR¹ is as defined above, at least two of R¹ groups per molecule beingalkenyl, f is an integer of 0 to 100, g is an integer of 0 to 5,000, his an integer of 0 to 500, k is an integer of 0 to 500, and2≤f+g+h≤5,000, (C) an organopolysiloxane having at least two hydrosilylgroups per molecule, represented by the general formula (6):(R³ ₃SiO_(0.5))_(p)(R³ ₂SiO)_(q)(R³SiO_(1.5))_(r)(SiO₂)_(s)  (6) whereinR³ is independently hydrogen or a C₁-C₁₂ monovalent hydrocarbon group,at least two of R³ groups per molecule being hydrogen, and p is aninteger of 0 to 100, q is an integer of 0 to 500, r is an integer of 0to 300, s is an integer of 0 to 300, and 2≤p+q+r≤500, and/or (D) ahydrosilyl-containing silphenylene compound represented by the generalformula (7):

wherein R³ is as defined above and m is an integer of 0 to 3, in suchamounts that a ratio of the total number of hydrosilyl groups incomponents (C) and (D) to the total number of alkenyl groups incomponent (A) and in component (B) if present ranges from 0.6/1 to 3/1.7. An addition curable resin composition comprising (A) a silphenyleneoligomer skeleton-bearing organosilicon compound having at least twoalkenyl groups per molecule, represented by the general formula (1):(R¹ ₃SiO_(0.5))_(a)(R¹ ₂SiO)_(b)(R¹SiO_(1.5))_(c)(SiO₂)_(d)Z_(e)  (1)wherein R¹ is independently a C₁-C₁₂ monovalent hydrocarbon group freeof aliphatic unsaturation or C₂-C₆ alkenyl group, at least two of R¹groups per molecule being alkenyl, Z is independently a group having theformula (2):

wherein R² is independently a C₁-C₁₂ monovalent hydrocarbon group, and nis an integer of 1 to 3, and a is an integer of 0 to 100, b is aninteger of 0 to 5,000, c is an integer of 0 to 500, d is an integer of 0to 500, e is an integer of 1 to 500, and 2≤a+b+c≤5,000, and (E) ahydrosilylation catalyst.
 8. A semiconductor package encapsulated with acured product of an addition curable resin composition comprising asilphenylene oligomer skeleton-bearing organosilicon compound having atleast two alkenyl groups per molecule, represented by the generalformula (1):(R¹ ₃SiO_(0.5))_(a)(R¹ ₂SiO)_(b)(R¹SiO_(1.5))_(c)(SiO₂)_(d)Z_(e)  (1)wherein R¹ is independently a C₁-C₁₂ monovalent hydrocarbon group freeof aliphatic unsaturation or C₂-C₆ alkenyl group, at least two of R¹groups per molecule being alkenyl, Z is independently a group having theformula (2):

wherein R² is independently a C₁-C₁₂ monovalent hydrocarbon group, and nis an integer of 1 to 3, and a is an integer of 0 to 100, b is aninteger of 0 to 5,000, c is an integer of 0 to 500, d is an integer of 0to 500, e is an integer of 1 to 500, and 2≤a+b+c≤5,000.